Yes. I talked to Kevin Medina, their sound tech, after a show in April and he confirmed that the bass tracks are programmed into Cacie's MacBook. I don't blame the band; it's likely they can't reasonably afford a touring bassist.
They also played "Thread" as the song that aired on television last night. It can be seen here.
oh no, how they can't afford it? Don't they know that I'd be happy to play bass for them and even add my money to the business! ; ) ..hell, if I lived in America of course hah, not in fucking Poland : ) ...anyway, I also understand that fact seriously, but they've got really interesting drum beats and this bass is also quite important, I hope they'll find someone to perform it.
And both these songs are amazing by the way.